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Welded pipe is formed by rolling flat coil or plate into a circular section and welding the seam along its length. It is the more economical production route and is well suited to structural, architectural and general industrial use. The welding methods most commonly referenced by their abbreviations are:
EFW -- Electric Fusion Welding
ERW -- Electric Resistance Welding
HFW -- High Frequency Welding
SAW -- Submerged Arc Welding (spiral-seam or long-seam)
Seamless pipe is pierced and drawn from a solid round billet, so there is no weld seam anywhere along its length or circumference. Because there's no seam to act as a potential weak point, seamless pipe is the standard choice for high-pressure applications -- oil and gas transport, chemical processing, and refinery piping -- where a welded seam would be the first place a failure could start.
Pipe grade is generally referenced against one of three standards -- DIN (German), EN, or ASTM -- and the table below cross-references the equivalent grade designation across all three for the most commonly ordered austenitic grades.
|
DIN Grade |
EN Grade |
ASTM Grade (Pipe) |
|
1.4301 |
X5CrNi18-10 |
ASTM A312 Grade TP304 |
|
1.4306 / 1.4307 |
X2CrNi19-11 / X2CrNi18-9 |
ASTM A312 Grade TP304L |
|
1.4401 |
X5CrNiMo17-12-2 |
ASTM A312 Grade TP316 |
|
1.4404 |
X2CrNiMo17-13-2 |
ASTM A312 Grade TP316L |
|
1.4571 |
X6CrNiMoTi17-12-2 |
ASTM A312 Grade TP316Ti |
|
1.4541 |
X6CrNiTi18-10 |
ASTM A312 Grade TP321 |
Full chemistry, mechanical properties and size ranges for each individual grade -- including SS 202, 304, 304L, 316, 316L, 321, 310 and 347H -- are covered on the Stainless Steel Pipe Grades page and each grade's own page.
Sanitary Pipe: used in food processing, dairy, and medical/biochemistry lines where the interior surface has to stay free of contamination and corrosion. ASTM A270 is the specification most commonly called for in sanitary tube.
Mechanical Pipe: used for hollow structural components, bearing housings and cylinder sections, commonly to ASTM A554 or A511, and readily formed into square, rectangular or custom profiles for chassis and machinery frames.
Polished Pipe: used where appearance and surface finish matter as much as strength -- handrails, balustrades and architectural trim -- typically in a brushed or mirror-polished finish that needs no additional protective coating.
Manufacturing stainless steel pipe since 1962 from our Mumbai facility, with both seamless and welded production and dimensional checks carried out on every batch before dispatch. We supply across the full profile range -- round, square, rectangular, seamless, welded, ERW and exhaust-grade -- and the full 200/300/H-series grade range, so a single order can be sourced from one supplier instead of several.
Siddhgiri Overseas is ISO certified for quality, occupational health & safety and environment management, and holds the import and export certification required to supply stainless steel pipe and tube to customers worldwide. Certificate copies are available on request for buyers who need them for their own compliance records.
Each dispatch is accompanied by standard industry documentation, including a Mill Test Certificate (MTC), typically issued to EN 10204 3.1, verifying the supplied material against the ordered grade. All pipe also undergoes dimensional checks before dispatch.
